Need some good .NET Design Pattern interview questions

Hello. I will be interviewing a few candidates for a senior architecture position that we have open at our company.
As an architect we expect them to be familiar with commonly used .NET Design Patterns.

Does anyone have some suggestions for some good interview questions? I am not looking for questions like: explain the Factory Pattern, but more like scenarios in which certain patterns are typically used.

The best way to understand the depth of knowledge a candidate might have in design pattern is by asking these questions...

1. What are all design pattern you have used in your project?
2. Explain a scenario where you have applied <any pattern name told in previous answer>PATTERN_NAME? and why did you applied this pattern?
3. How long you have been using design patterns for the projects you had worked?

First you need to ask them if they know the basic OO principles: SOLID and GRASP.

The Design Patterns are nothing more than concrete implementations of these principles.

Then you delve into the Design Patterns specifics.

In real world very often you may not use a Design Pattern as it is in a book, what matters is to know and understand the principles and the ideas behind OO. Then you can do a good job when you architect and design an application.